community-driven open specification within the OpenAPI Initiative

 The OpenAPI Specification (OAS) defines a standard, programming
 language-agnostic interface description for HTTP APIs, which allows both humans
 and computers to discover and understand the capabilities of a service without
 requiring access to source code, additional documentation, or inspection of
 network traffic. When properly defined via OpenAPI, a consumer can understand
 and interact with the remote service with a minimal amount of implementation
 logic. Similar to what interface descriptions have done for lower-level
 programming, the OpenAPI Specification removes guesswork in calling a service.